Electrical space discharge tube



Feb. 24, 1942.-

N. B. KRIM ELECTRICAL SPACE DISCHARGE TUBE Filed Aug. 17, 1940 FIQI Fl 6-. Z.

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KRIM, 7

Patented Feb. 24, 1942,

PATENT "(OFFICE I assignor to Raytheon Production Corporation, Newton,

Mass a corporation of Delaware Application August 17;, 1940, Scrial No. 353,107

A 2 Claims. (crestevis) This invention relates to an electrical space discharge tube'of the vacuum type in which the dimensions of the tube are reduced to relatively smallvalues. In such a tube the problem of pro-Q viding lead-in conductors for multiple grid tubes through a single press, so as to avoid shortcircuiting, is particularly acute.

An object of this invention is to provide leadin conductors in such a tube so as to avoid short circuiting with close spacing.

The foregoing and other objects Will b'e'best understood from the following description of an exemplification thereoflreference being had to the accompanying drawing, wherein:

Fig. l is a cross-section of my novel tube taken along line 1-4 of Fig. 3;

Fig. 2 is a right-hand View of the electrode assembly shown in Fig. 1 with the glass envelope shown in cross-section; and

Fig. 3 is a top view of the electrode assembly of Fig. 1. v

The tube illustrated contains an electrode assembly consisting of, an anode I, a filamentary cathode 2, and a plurality of grids 3, 4 and 5. The grids are wound upon and supported by grid side rods 6-B, 1-4 and 8--8, respectively. Proper spacing and support of the electrodes are provided by upper and lower insulating spacers 99, preferably of mica. The spacers 9--9 are cut away to provide resilient projections! which are adapted to resiliently engage the inner walls of the glass envelope. The spacers 9 are each provided with a triangular slot H having a rectangular recess in the base thereof in order to receive and support one of the side rods 6 of the grid 3.

The filamentary cathode 2 is retained in the apex of each of the triangular slots II. In order to support the lower end of the filamentary cathode 2, a U-bracket I3 is secured to the lower spacer 9 and projects from the lower side thereof. The bracket l3 has welded thereto a tab I4 which in turn is welded to the lower end of the fila-, mentary cathode 2, and serves as a mechanical support and electrical connector therefor. A conducting spring member i is welded at one end to the upper end of the filamentary cathode 2, and at its other end to one of the side rods 8 of the grid 5. The spring l5 pulls upwardly on the filamentary cathode 2, and maintains the proper tension thereon. Furthermore, said spring projects beyond the apex of the upper triangular slot ll 50 as to force the upper end of the filamentary cathode into the apex of said triangular slot. Likewise the tab I4 is located beyond the apex of the lower triangular slot ll so as to maintainthe'lower end of the filamentary cathode in said apex.

The anode l is provided with a plurality of .tabs I5 at its upper edge and aplurality of tabs I! at its lower edge. These tabs are bent over onto the upper and lower surfaces of the upper and lower spacers 9, respectively, and serve to maintain the electrode assembly in its assembled form, whereby it may be readily handled as a unit before insertion into the glass envelope. As an additional means for'retaining the grid 5 in place within the electrode assembly, one of the side rods 8 may be provided with stops l8-|8 welded to the upper and lower ends of said side rod and bearing against the upper and lower faces of the upper and lower spacers 9, respectively.

In order to avoid electrical breakdown or shortcircuiting from occurring between the lead-in wires sealed through the stem, a special arrangement of such lead-in wires is provided. The anode is provided'with a connector I!) which extends from the anode over to one side of the tube where it is connected to a lead-in conductor 20. Adjacent to said lead-in conductor is an additional lead-in 23 which is connected to the side rod I of the grid 4. It will be noted that one of the side rods 8 of the grid 5 lies between the lead-ins 20 and 23. By not locating the lead-in for the grid 5 at this point, additional room is available for suificient spacing of the lead-ins 20 and 23. Next to the lead-in 23 is a lead-in conductor 2| which is welded to the bracket l3. It will be noted that one of the side rods 6 of the grid 3 is located substantially in line with the lead-in 2|, but since a connection is not made to said side rod 6, the space is available for said lead-in 2i. Adjacent said lead-in is a conductor 22 which is Welded to the other side rod 6 of the grid 3. The next side rod 1 of the grid 4 is left free, and substantially adjacent it is located a lead-in conductor 24 which, however. is welded to the other side rod 8 of the grid 5. The above arrangement of lead-in conductors makes maximum use of the space available in order to enable the necessary lead-ins to be utilized without danger of short circuiting between said lead-ins and the conductors leading thereto. In this connection it will be noted that each successive leadin conductor is connected to side rods which lie successively on opposite sides of the grids involved.

In order to eliminate vibration of the filament, a spring Wire 26 is provided. One end of this spring wire is welded to a tongue 21 formed in the side wall of the anode I by cutting a U-shaped slot therein. The spring wire 26, except for the point at which it is welded to the tongue 21, is covered with an insulating coating 28 bearing against the filament. Any tendency for vibration to occur is absorbed by the spring wire 26 and the insulating coating 28 thereon;

The above electrode assembly is inserted as a unit within a straight-sided glass tube 29. The lower end of this tube is heated and softened sufficiently so that it may be pressed to make the press or seal 30. The upper end of the tube 29 is provided with the usual tubulation, exhausted and sealed off at 3|.

The copending applications of Percy L. Spencer, Serial No. 346,554, filed July 20, 1940, and Alan C. R'ockwood, Serial No. 353,108, filed August 17, 1940, more fully describe and claim certain features of the construction as illustrated in this application.

Of course it is to be understood that this invention is not limited to the particular details as described above as many equivalents will suggest themselves to those skilled in the art. For example, the invention can be applied to tubes of other types in which other numbers of grids might be used. Various other changes embodying the teachings of this invention will suggest themselves to those skilled in the art. It is accordingly desired that the appended claims be given a broad interpretation commensurate with the scope of the invention within the art.

What is claimed is:

1. An electrical space discharge tube comprising an envelope containing a filamentary cathode, an anode, and a plurality of grids interposed between said cathode and said anode, a press in the wall of said envelope, a plurality of conductors sealed in said press and disposed in a row, the conductor at one end of said row being connected to one end of said cathode, the conductor at the other end of said row being connected to said anode, one of said grids being connected to one of said end conductors, the central conductor in said row being connected to the other end of said cathode, the conductors located alternately on opposite sides of said central conductor being connected to successive grids.

2. An electrical space discharge tube comprising an envelope containing a filamentary cathode, an anode, and a plurality of grids interposed between said cathode and said anode, a press in the wall of said envelope, a plurality of conductors sealed in said press and disposed in a row, the conductor at one end of said row being connected to one end of said cathode, the conductor at the other end of said row being connected to said anode, the outermost grid being connected to the end conductor connected to said cathode, the central conductor in said row being connected to the other end of said cathode, the conductors located alternately on opposite sides of said central conductor being connected to successive grids.

NORMAN B. KRIM. 

